The application is the applying date is on June 6th, 2006, application number is 200610083389.6 and name is called the divisional application of the invention of " utilizing statistical Process Control to control the method and apparatus of soot blowing ".
Background technology
Various industry and non-industrial applications all use the boiler of fuel burning, and typically for passing through one of various types of fuel of burning, such as coal, combustion gas, oil, waste material etc., become heat energy by chemical energy.The exemplary use of one of the boiler of fuel burning is in thermoelectric generator, and the fuel cause of wherein burning in boiler produces steam through the water of pipeline pipeline a large amount of in boiler, and then these steam are used for again generating electricity in one or more turbine.The output of thermoelectric generator is the function producing heat in boiler, and wherein this heat is determined by the fuel quantity etc. that can burn per hour.In addition, the heat transfer efficiency of the boiler for combustion fuel is also depended in the output of thermoelectric generator.
The fuel of some type, the such as burning of coal, oil, waste material etc., boiler each on the surface, comprise boiler inner wall and be carried through on the pipeline outer wall of water of boiler, producing a considerable amount of cigarette ash, slag, ashes and other deposits (being commonly referred to " cigarette ash ").The cigarette ash be deposited on boiler can produce various injurious effects to the coefficient of overall heat transmission from boiler to water, and therefore produces injurious effects to the efficiency of the arbitrary system using this boiler.The cigarette ash problem in the fuel burning boiler of other fuel of coal combustion, oil and generation cigarette ash must be solved, to maintain the expection efficiency in boiler.Although and the fuel burning boiler of not all can produce cigarette ash, for the residue of this patent, term " boiler of fuel burning " is used to refer to those boilers producing cigarette ash.
Develop various solution, solved by the generation of smoke deposition in the boiler of fuel burning boiler and the problem that occurs and cause.One method uses flue blower, by producing machinery and thermal shock, removes the cigarette ash fouling accumulated in boiler surfaces.Another kind method uses various types of flue blower, be positioned at the gas side on boiler wall and/or other heat exchange surfaces, cleaning material is sprayed by nozzle, these flue blowers use in various medium any one, such as saturated vapor, superheated steam, compressed air, water etc., to remove the cigarette ash on boiler.
Soot blowing can have an impact to the efficiency of operation fuel burning boiler and expenditure.Such as, if apply insufficient soot blowing in the boiler, then will cause excessive soot deposits on the surface at various steam conveying pipe, thus cause the lower coefficient of overall heat transmission.In some cases, insufficient soot blowing may cause " permanent dirt " in fuel burning boiler, this means that the soot deposits in boiler is so many, so that these deposits do not remove by any extra soot blowing.In this case, may need the forced stoppage of boiler attendance, to repair the problem of too much soot deposits, and boiler maintenance personnel may must use hammer and chisel, manually removes these soot deposits.Such forced stoppage is only exemplary, but is also destructive for using the system of this fuel burning boiler.
On the other hand, soot blowing too much in fuel burning boiler may cause the increase of energy cost operating flue blower, otherwise can be used for the waste of steam of operating turbine, etc.Too much soot blowing also may be thinning with boiler wall heat pipe, and pipe leakage etc. are associated, this forced stoppage that boiler may be caused to use.Therefore, need carefully to control soot blowing process.
In history, the soot blowing in station boiler has mainly become a kind of special practice, and this generally depends on the judgement of boiler attendance person.A kind of like this adhoc approach creates very inconsistent result.Therefore, importantly more effectively, and manage soot blowing process by this way, to maximize the efficiency of boiler attendance, and minimize and operate relevant cost to soot blowing.
One is used for determining boiler section cleannes, and the universal method being used for controlling soot blowing operation is method based on general principle, and its requires to measure in the flue-gas temperature of boiler section inlet and outlet and vapor (steam) temperature.But, because the direct measurement of flue-gas temperature always is infeasible, therefore frequent from the flue-gas temperature that air heater outlet place is measured, along multiple somes backwards calculation flue-gas temperatures of smoke path.The method is highstrung for the disturbance of air heater outlet flue gas temperature and change, and this usually can cause incorrect result.And the method is a kind of steady state method, and therefore can not be suitable for usual the run into transient process of various boiler section well.
Another kind of for determining the boiler section cleannes of fuel burning boiler, and the universal method being used for controlling soot blowing operation in fuel burning boiler is the method based on empirical model, it depends on empirical mode, as neural network model, fitting of a polynomial model, etc.The a large amount of empirical datas with many relating to parameters should be usually required, such as fuel flow rate, air flow rate, air themperature, water/vapor (steam) temperature, the burner elevation angle based on the method for empirical model, etc.Unfortunately, a large amount of data make data collection process tedious dull, and are easy to occur a large amount of mistakes in data acquisition.
Detailed description of the invention
Statistical process control system uses for the consistent soot blowing operation of the heat-exchange section of such as fuel burning boiler, gather the heat absorption data of this heat-exchange section and analyze the distribution of heat absorption data and the various parameters of heat absorption distribution, to readjust the operation of described soot blowing.This statistical process control system can arrange expection lower heat absorption limit and the expection heat absorption upper limit, and is compared in they and actual lower heat absorption limit and the actual heat absorption upper limit respectively, readjust to determine whether to operate soot blowing.
Generally speaking, statistical process control system described herein and the method based on general principle are compared more reliable with the method based on empirical model, and are easy to be embodied as the statistical process control system only needing heat absorption data to realize.And, because statistical process control system described herein uses heat absorption data, the disturbance of it and flue-gas temperature and noise have nothing to do, and generally can not be subject to its impact, therefore provide more unified control for the operation of flue blower and the cleannes of heat-exchange section.
Generally speaking, each time dependent heat absorption in some place is measured in the realization of statistical process control system, to determine the heat absorption difference before and after soot blowing operation, and calculate various statistical Process Control measurement result, to determine the validity that soot blowing operates based on this heat absorption statistics.This statistical process control system is that the heat-exchange section of boiler or other machines sets up consistent soot blowing operation, and reduction control soot blowing operates necessary data volume.
Fig. 1 illustrates the block diagram of the boiler steam cycle of typical boiler 100, and this boiler 100 may be used for such as thermal power plant.Boiler 100 can comprise various section, and steam or water can in a variety of manners, such as superheated steam, reheated steam, etc. flow through these sections.Although the boiler shown in Fig. 1 100 has horizontally disposed various boiler section, but in reality is implemented, one or more in these sections can vertically place, especially because the various boiler section of heating, such as, in the water wall absorption section flue gas of steam is vertical rising.
This boiler 100 comprises water wall absorption section 102, elementary overheated absorption sections 104, overheated absorption sections 106 and reheating section 108.In addition, boiler 100 also can comprise one or more desuperheater 110 and 112, and economizer 114.The main steam that boiler 100 produces is used for driving high pressure (HP) turbine 116, and is used for pressing (IP) turbine 118 in driving from the reheated steam of the heat of reheating section 108.Usually, boiler 100 can also be used to drive low pressure (LP) turbine, not shown in FIG.
Primary responsibility produces the water wall absorption section 102 of steam, and comprise many pipelines, steam enters drum barrel by these pipelines.The feedwater entering water wall absorption section 102 can be pumped through economizer section 114.When in water wall absorption section 102, this feedwater absorbs a large amount of heat.This water-cooling wall section 102 has steam drum, and this steam drum had both comprised water and also comprised steam, and the water level in this drum barrel also must carry out careful control.The steam gathered at steam drum top is fed to elementary overheated absorption sections 104, and be next fed to overheated absorption sections 106, vapor (steam) temperature is elevated to very high level by together.The main steam exported from overheated absorption sections 106 drives pressure turbine 116 to generate electricity.
Once main steam drives HP turbine 116, then steam is sent to reheating absorption sections 108, and is used for driving IP turbine 118 from the reheat heat steam that reheating absorption sections 108 exports.Desuperheater 110 and 112 can be used for control to arrive expection set-point final vapor (steam) temperature.Finally, steam from IP turbine 118 can be fed through LP turbine (not shown) herein and arrive stram condenser (not shown) herein, be liquid there by steam-condensation, and be used for next make-up cooling water from various boiler feed pump pumping, this circulation again accent starts.The economizer 114 being arranged in the waste gas streams of the heat of discharging from boiler uses this hot gas, so that before feedwater enters water wall absorption section 102, by extra heat trnasfer to this feedwater.
Fig. 2 is the schematic diagram of boiler section 200, and this boiler section has the heat exchanger 202 be arranged in from the smoke path of boiler 100.Boiler section 200 can be any one a part in above-mentioned various heat-exchange section, such as elementary overheated absorption sections 104, reheating absorption sections 108, etc.Those of ordinary skill in the art can understand, although the boiler section 200 of this example can be positioned at the specific part of boiler 100, in this patent, illustrated flue blower control method can be applied in this boiler any section that heat exchange and soot build-up may occur.
Heat exchanger 202 comprises the many pipelines 204 for transporting steam, and these steam mix with shower water in blender 206.The mixture of water and steam is also converted into superheated steam by this heat exchanger 202.Schematically show the flue gas inputing to boiler section 200 with arrow 209, and schematically show the flue gas leaving boiler section 200 with arrow 211.Boiler section 200 is expressed as and comprises six flue blowers 208,210,212,214,216 and 218, for removing the cigarette ash on heat exchanger 202 outer surface.
Operator can control the operation of flue blower 208,210,212,214,216 and 218 by computer 250.Computer 250 can be designed on memory 252, store one or more computer program, this memory can be random-access memory (ram), the forms such as read-only storage (ROM), wherein such program can be suitable for the enterprising row relax of CPU (CPU) 254 at computer 250.User can be communicated with computer 250 by i/o controller 256.Each in the various parts of computer 250 all can be communicated by internal bus 258 mutually, and this internal bus 258 also can be used for communicating with external bus 260.Computer 250 can use external communication bus 260, and with each flue blower 208,210,212,214,216 communicate with each in 218.
Flue blower 208-218 can operate according to specific soot blowing sequence, this sequence prescription will to open in flue blower 208-218 each order, the operating frequency of flue blower 208-218, the time span that each flue blower opens, etc.Although the certain portions of giving of fuel burning boiler can have many different heat-exchange section, the steam and the supply of water that may be used for soot blowing operation are limited.Therefore, each heat-exchange section is assigned to priority, and the flue blower in heat-exchange section operates according to this priority.The flue blower in heat-exchange section with higher priority can receive required water and steam to operate fully, and the flue blower in heat-exchange section with lower priority can only operate when obtaining required water and steam.Will describe in further detail as following, the program that can perform according to the flue blower for controlling specific heat-exchange section, changes the priority of specific heat-exchange section.
Fig. 3 illustrates the flow chart of heat absorption statistics calculation program 300, and this program can be used for calculating any one in each section of boiler 100, the heat absorption statistics of such as boiler section 200.Heat absorption statistics calculation program 300 can be implemented as software, hardware, firmware or is embodied as its any combination.When being embodied as software, heat absorption statistics calculation program 300 can be stored on read-only storage (ROM), random-access memory (ram), or is stored on other memory devices any that the computer for performing soot blowing process control block (PCB) 300 uses.Heat absorption statistics calculation program 300 can be used for the heat absorption statistics of the section only calculating boiler 100, or alternatively, can be used for calculating the heat absorption statistics of all heat-exchange section in boiler 100.
Frame 302, by setting up the initiation sequence (current operation sequence) of operation, starts the calculating of heat absorption statistics.Above-mentioned current operation sequence can be described by the parameters of definition time line, this timeline such as, for operating boiler section, in the multiple flue blowers in boiler section 200 any one.Such as, the execution of heat absorption statistics calculation program 300 can specify the frequency of opening flue blower 208, keep flue blower 208 to be in the time span of opening, and between two cycles continuous print opening time, close the time span of flue blower 208.
Frame 302 also gathers the various data relevant with the steam stored with flow through boiler section 200.Such as, frame 302 can gather the temperature and pressure of the steam entering boiler section 200, and can calculate and use Hiindicate boiler section 200 enter enthalpy (enthalpy is the heat content of fluid, and its unit is Btu/lb), from boiler section 200 discharge vapor (steam) temperature and pressure, use Hothe discharge enthalpy of boiler section 200 indicated is lbs/Hr with F(unit) steam that indicates flows into the flow rate of boiler area section 200, etc.
The data that frame 304 uses frame 302 to gather, calculate and store the heat absorption in boiler section 200.In this example, can be given as with the heat absorption of the boiler section 200 of Q sign:
Q＝F*(Ho-Hi)
As selection, in some heat-exchange section, such as, in the sub-segments of the water wall absorption section 102 of boiler 100, heat flow transducer can be utilized directly to measure heat absorption Q.
The heat absorption data amount that frame 304 gathers and stores evaluated by the frame 306 of Fig. 3.Such as, user can specify the observed result number that must be gathered by soot blowing process control block (PCB), and this regulation that gathered data and user provide by frame 306 in this case compares.If required more data determined by frame 306, control to rotate back into frame 302.
When the heat absorption data acquiring sufficient amount determined by frame 306, gathered data determined by frame 308, and whether followed normal distribution distributes.User can provide confidence level, and heat absorption statistics calculation program 300 needs to determine that whether this heat absorption data is with this confidence level normal distribution.Such as, user can specify that heat absorption data must with the confidence level normal distribution of 95 percent, etc.If the confidence level normal distribution that heat absorption data fails to specify determined by frame 308, this may be the result of irregular soot blowing sequence, then the current operation sequence for operating flue blower in boiler section 200 revised by frame 309, thus makes operation sequencing more consistent.Then, control to rotate back into frame 302, gather more data to obtain more observation stations of heat absorption data.
If frame 308 determines that this heat absorption data is normal distribution, then frame 310 calculates the multiple heat absorption statistical data being used for boiler section 200.Such as, frame 310 can calculate heat absorption mean, heat absorption intermediate value, heat absorption variance, heat absorption standard deviation, the heat absorption degree of bias, etc.
After this, the heat absorption statistical data that frame 310 calculates evaluated by frame 312.Especially, frame 312 can evaluate the heat absorption statistical data of the many measurements provided relative to the user of heat absorption statistics calculation program 300, or relative to the heat absorption statistical data of much industrial average, etc.
In the realization of heat absorption statistics calculation program 300, frame 312 can be equipped with target lower control and target upper control limit, and the actual heat absorption of boiler section is evaluated relative to this bound.Alternatively, the long-term heat absorption statistical data that heat absorption statistics calculation program 300 can use frame 310 to calculate, calculates this target lower control and target upper control limit.Such as, the execution of heat absorption statistics calculation program 300 can use heat absorption mean and heat absorption standard deviation, determines this target lower control and target upper control limit.
After frame 312 have rated heat absorption statistic, frame 314 determines whether the current operation sequence necessarily changing flue blower.Such as, frame 314 can determine necessarily to change the frequency of opening flue blower, keeps flue blower to be in the time span of opening, and between two continuous print unlatching cycles, close at least one in the time span etc. of flue blower.In the one of heat absorption statistics calculation program 300 realizes, frame 314 can be determined if actual heat absorption mean is lower than target lower control, then necessarily change one or more operating parameters of current operation sequence.
If frame 314 determines necessarily to change the current operation sequence of flue blower, then frame 316 calculates the change that will to be applied in current operation sequence parameters any one.The various heat absorption statistics that frame 316 can use frame 310 to calculate, determine the change that will be applied to current operation sequence parameters.Such as, in the realization of heat absorption statistics calculation program 300, frame 314 can be determined to be applied to the change that flue blower will be held open the time span of state, should be the function of difference between actual heat absorption mean and target lower control.But frame 314 can also determine that this soot blowing is high-efficiency operation, and the current operation sequence of flue blower need not be changed, control in this case to forward frame 302 to, to continue monitoring this soot blowing process and without any change.
It should be noted that, although heat absorption statistics calculation program 300 illustrates in fig. 2, and be described above about boiler section 200, but heat absorption statistics calculation program 300 can also be applied to other heat-exchange section any of boiler 100.And although be performed the function figure that frame 312-316 performs by three different frames in heat absorption statistics calculation program 300, in alternative realization, these functions also can perform by single frame or by single program.
Fig. 4 A illustrates the flow chart of the realization of statistical Process Control program 350, and this program can perform the function of frame 312-316.Frame 352 can determine the expection distribution character of the heat absorption values of specific heat-exchange section.The determination of these characteristics can comprise select target lower control limit QlCL, target upper control limit QuCL, and other characteristics of the expection distribution of this specific heat-exchange section.Subsequently, frame 354 can use following formula to calculate heat absorption mean Qmean:
Wherein N represents the number of the heat absorption observed result comprised in given sampling, and Qii-th observation
border upper limit Qm+3 σ.Although in this realization of statistical Process Control program 350, actual lower limit Qm-3 σ and actual upper bound Qm+3 σ is only heat absorption mean Qmeanwith the function of heat absorption standard deviation Q σ, but in alternative realization, the alternative statistical value of such as variance can be used for calculating alternative actual lower limit and alternative actual upper bound.And, although in this example, actual lower limit Qm-3 σ and actual upper bound Qm+3 σ is defined as distance heat absorption mean Qmeanthere are 3 Sigma points (3 σ), but in practice, also can use and be positioned at distance heat absorption mean Qmeanthere is the alternative actual lower limit Qm-x σ of x Sigma points (wherein x is the numeral that the user of statistical Process Control program 350 can select) and alternative actual upper bound Qm+x σ.If necessary, x can be integer or can be any real number.
Subsequently, frame 360 is by actual lower limit Qm-3 σ and target lower control QlCLcompare, and by actual upper bound Qm+3 σ and target upper control limit QuCLcompare.Frame 360 can be equipped with a series of rule, and these rules can be used for performing this based on this comparative result and compare, and frame 360 can generate the decision about needing to change one or more parameters of current operation sequence.
To the actual lower limit Qm-3 σ of specific heat-exchange section and the evaluation of actual upper bound Qm+3 σ, provide the information of the heat absorption values actual distribution about this specific heat-exchange section.By comparing actual lower limit Qm-3 σ and target lower control QlCL, and compare actual upper bound Qm+3 σ and target upper control limit QuCL, the frame 360 of statistical Process Control program 350 is determined to measure one period of specific period, and whether the actual distribution of heat absorption values equal the expection distribution of heat absorption values approx.
If frame 360 determines that actual lower limit Qm-3 σ equals target lower control Q approxlCL, and compare actual upper bound Qm+3 σ and be approximately equal to target upper control limit QuCL, then the actual distribution of heat absorption values equals the expection distribution of heat absorption values approx.In this case, frame 360 can determine that the current operation sequence for operating flue blower suitably plays a role, or successfully achieves the expection control to soot blowing operation.Therefore, any change need not be carried out to any operating parameter of current operation sequence, and as shown in the path A of Fig. 4 A, control to rotate back into frame 354.
In some cases, frame 360 can determine target lower control QlCLbe greater than actual lower limit Qm-3 σ (QlCL> Qm-3 σ), and target upper control limit QuCLalso actual upper bound Qm+3 σ (Q is greater thanuCL> Qm+3 σ).As shown in the distribution 380 in Fig. 4 B, this result (the path B in Fig. 4 A) represents that the actual distribution of heat absorption observed result is positioned at the left side of expection distribution.In this case, frame 362(it can perform with the frame 316 of Fig. 3) free time continuously between soot blowing operation in current operation sequence can be reduced, or improve the soot blowing priority of heat-exchange section, so that by the actual distribution of heat absorption observed result to right translation.Lower free time or higher blowing priority can cause soot blowing operation frequently, and therefore remove the soot deposits of higher quantity, and this will cause the distribution narrowed of heat absorption data to by target lower control QlCLwith target upper control limit QuCLthe expection level of regulation.The knots modification of free time and blowing priority rule of thumb can be determined by the user of boiler 100.
On the other case, frame 360 can determine target lower control QlCLlower than actual lower limit Qm-3 σ (QlCL< Qm-3 σ), and target upper control limit QuCLalso lower than actual upper bound Qm+3 σ (QuCL< Qm+3 σ).As shown in the distribution 382 in Fig. 4 B, this result (the path C in Fig. 4 A) represents that the actual distribution of heat absorption observed result is positioned at the right side of expection distribution.Usually, this situation can represent too much soot blowing.In this case, frame 364 can increase the free time in current operation sequence continuously between soot blowing operation, or reduces the soot blowing priority of heat-exchange section, so that by the actual distribution of heat absorption observed result to left.Higher free time or lower blowing priority can cause more low-frequency soot blowing to operate, and therefore remove the soot deposits of smaller amounts, and this will cause the distribution broadening of heat absorption data to by target lower control QlCLwith target upper control limit QuCLthe expection level of regulation.The knots modification of free time and blowing priority rule of thumb can be determined by the user of boiler 100.
As selection, frame 360 can determine target lower control QlCLhigher than actual lower limit Qm-3 σ (QlCL> Qm-3 σ), and target upper control limit QuCLlower than actual upper bound Qm+3 σ (QuCL< Qm+3 σ).As shown in the distribution 384 in Fig. 4 B, this result (the path D in Fig. 4 A) represents that the actual distribution of heat absorption observed result is wider than expection distribution.In this case, frame 366 is by current actual heat absorption Qactualwith heat absorption mean Qmeancompare.If Q determined by frame 366actual< Qmean, then frame 368 reduces the free time between the operation of continuous soot blowing, or improves the soot blowing priority of heat-exchange section.Lower free time or higher blowing priority can cause soot blowing operation frequently, and therefore remove the soot deposits of higher quantity, and this will cause working control lower limit Qm-3 σ towards expection lower control limit QlCLtranslation.The knots modification of free time and blowing priority rule of thumb can be determined by the user of boiler 100.
On the other hand, if Q determined by frame 366actual> Qmean, then frame 370 increases the free time between the operation of continuous soot blowing, or reduces the soot blowing priority of heat-exchange section.Higher free time or lower blowing priority can cause the soot blowing of lower frequency to operate, and therefore remove the soot deposits of smaller amounts, and this will cause working control upper limit Qm+3 σ towards expection upper control limit QuCLtranslation.The knots modification of free time and blowing priority rule of thumb can be determined by the user of boiler 100.
Further, frame 360 can determine target lower control QlCLlower than actual lower limit Qm-3 σ (QlCL< Qm-3 σ), and target upper control limit QuCLbe greater than actual upper bound Qm+3 σ (QuCL> Qm+3 σ).As shown in the distribution 386 in Fig. 4 B, this result (the path E in Fig. 4 A) represents that the actual distribution of heat absorption observed result is than expection narrowly distributing.In this case, frame 372 is by current actual heat absorption Qactualwith heat absorption mean Qmeancompare.If Q determined by frame 372actual< Qmean, then frame 374 increases the free time between the operation of continuous soot blowing, or reduces the soot blowing priority of heat-exchange section.Higher free time or lower blowing priority can cause the soot blowing of lower frequency to operate, and therefore remove the soot deposits of smaller amounts, and this will cause working control upper limit Qm+3 σ towards expection upper control limit QuCLtranslation.The knots modification of free time and blowing priority rule of thumb can be determined by the user of boiler 100.
On the other hand, if Q determined by frame 372actual> Qmean, then frame 376 reduces the free time between the operation of continuous soot blowing, or improves the soot blowing priority of heat-exchange section.Lower free time or higher blowing priority can cause soot blowing operation frequently, and therefore remove the soot deposits of higher quantity, and this will cause working control lower limit Qm-3 σ towards expection lower control limit QlCLtranslation.The knots modification of free time and blowing priority rule of thumb can be determined by the user of boiler 100.
Subsequently, the validity of the process that frame 354-376 takes evaluated by frame 378, to determine target upper control limit QuCLwith target lower control QlCLcurrent selection control specific heat-exchange section soot blowing operation in whether be effective.Frame 378 can gather the various statistics relevant with the translation of distribution curve 380-386 on some of the operation of frame 354-376 circulates.If the end in these circulations determined by frame 378, distribution curve 380-386 moves to new position significantly, such as with the position that (Fig. 4 B's) distribution curve 384 represents, then frame 378 can determine that the process that frame 354-376 takes is invalid in the slagging avoiding heat-exchange section, therefore control is rotated back into frame 352, and ask user's select target upper control limit Q of statistical Process Control program 350uCLwith target lower control QlCLnew numerical value.
Although the wide distribution of the heat absorption values as shown in curve 380 can represent that the average heat transfer efficiency of heat-exchange section does not change in time, each observed result of heat transfer efficiency more may be different from average heat transfer efficiency.On the other hand, although the narrow ditribution of the heat absorption values as shown in curve 382 can represent that the average heat transfer efficiency of heat-exchange section does not change in time, each observed result of heat transfer efficiency less may be different from average heat transfer efficiency.
Heat absorption values distribution as shown in distribution curve 384 can represent soot deposits (slagging) due to quantity higher in heat-exchange section, the overall reduction of the heat transfer efficiency of heat-exchange section to left.On the other hand, the overall raising that can represent the heat transfer efficiency of heat-exchange section to right translation of the heat absorption values distribution as shown in distribution curve 386.The efficiency of this raising may be the result than soot blowing rate that must be higher, and may damage the various water and steam carrier pipes in heat-exchange section.
Although the one that Fig. 4 A-4B illustrates statistical Process Control program 350 realizes, Fig. 5 illustrates another kind of statistical Process Control program, and this program can be used for the permanent slagging determined in the heat-exchange section of boiler 100.Specifically, Fig. 5 illustrates slagging detection program 400, the distributed data of the heat absorption change that this program appraisal produces due to soot blowing, and heat absorption change mean Δ Qmeanand the correlation in specific heat-exchange section between soot blowing frequency, to determine any permanent slagging in specific heat-exchange section.
A series of distribution curve 450-454 of this situation Fig. 6 further illustrate, and each wherein in curve 450-454 all represents the distribution of the heat absorption change value Δ Q of specific heat-exchange section within the specific period, and wherein Δ Q can be defined as:
Δ Q=Qafter soot blowing-Qbefore soot blowing
Such as, curve 450 can represent the expection distribution of the heat absorption change value of specific heat-exchange section.As shown in Figure 6, in the ideal case, heat absorption change mean Δ Qmeanthe value of approximate 100 can be had.But due to permanent slagging (namely soot blowing is no longer valid), curve 450 can move to the position represented by curve 452, wherein actual absorption change mean Δ Qmeancan become to be approximately equal to and only have 80 or less.This slagging detection program 400 can be used for this slagging determined in heat-exchange section.
The class of operation of the frame 402-409 of slagging detection program 400 is similar to the operation of the frame 302-309 of heat absorption statistics calculation program 300, except frame 302-309 calculates the various statistics about the heat absorption Q of specific heat-exchange section, and frame 402-409 calculates the various statistics about the heat absorption change Δ Q of specific heat-exchange section.Subsequently, heat absorption data is divided into the part on different time by frame 410.Such as, if slagging detection program 400 has heat absorption data associated therewith, the operation of the heat-exchange section of such as month, then this heat absorption data can be divided into several groups of different data by frame 410 in time.Alternatively, frame 410 can store last fixed cycle number destination data really on rolling basis, thus only to the data analysis of last month, and abandon all data from previous periodic.
Frame 412 calculates the average of the difference group data provided by frame 410.Such as, frame 412 can calculate the Change of absorption value average of previous every day moon.Subsequently, frame 414 analyzes these values to determine whether there is a kind of tendency in these data.Specifically, frame 414 is determined whether this average shows and is temporally anyly gradually fallen or edge up.Gradually falling of average can represent heat-exchange section towards the trend of permanent slagging, and to carry out changing in the practice of current soot blowing be required.If the displacement in Change of absorption average detected, then correlation analysis can be performed.
Frame 418 calculating Corrm, f represents, the heat absorption change mean Δ Q of specific heat-exchange sectionmeanand the correlation in this specific heat-exchange section between soot blowing frequency.Frame 420 can determine correlation Corrm, and whether f is higher than the given threshold value in specific confidence level.If correlation Corrm, f are higher than given threshold value, this represents heat absorption change mean Δ Qmeanto left significantly with soot blowing frequency dependence, then frame 420 can by control be returned to frame 402, to continue the operation of the slagging detection program 400 of its normal mode.But if frame 418 determines this correlation not higher than given threshold value, then frame 420 just notifies user, may there is the situation of permanent slagging in evaluated heat-exchange section.Although it should be noted that the above-mentioned realization of slagging detection program 400 uses heat absorption change mean Δ Qmeanand the correlation between soot blowing frequency, but in alternative embodiments, equally also can use heat absorption change mean Δ Qmean, and between time span flue blower being remained on opening during each sequence, or and some other parameter of current operation sequence between correlation.
Although aforementioned texts has set forth the detailed description of the numerous different embodiment of the present invention, be to be understood that the word of the claim that scope of the present invention is finally proposed by this patent limits.This detailed description should be understood to be only exemplary, but not describes all possible embodiment of the present invention, even if because describing all possible embodiment is not impossible words, be also unpractical.The technology utilizing current techniques or develop after this patent submission date, can realize numerous alternate embodiments, these embodiments will drop on limit claim of the present invention scope within.
Therefore, without departing from the spirit and scope of the present invention, multiple improvement and change can be carried out to the technology described and illustrate and structure herein.Therefore, be to be understood that method and apparatus described herein is only exemplary, but not limit the scope of the invention.